This invention is directed to a filter system such as a cartridge filter system that can be used, for example, with a dust collector as used in cabinetmaking, carpentry and similar trades, in which a process dust is directed from dust producing equipment to a dust storage drum and in which the air that is separated from the dust is returned through a HEPA or similar final air filter to the ambient.
The needs of the customer for a given filter may vary, and in some cases, a filter with a larger filter area is needed. However, larger filters are more expensive to produce and to ship, and can be difficult to install. There is a need for a simple way to customize the filter size to the customer's needs, and to reduce the cost of shipping and reduce the difficulty in installing very large filters.
The solution we propose is a modular stacking filter system, of the type disclosed and shown in the attached drawings Figures. The filters of similar cross section are stacked one atop another and held together using stacking clamps. A number of sets of these clamps are distributed around the end flanges of the mating two filters. These clamps can, for example, comprise hook members that fit over the rims of the cartridge filter caps.
Favorably, there is a larger diameter seal or gasket on one end of the filter and a smaller diameter seal or gasket on the other end, so that the facing ends of the two stacked filter cartridges will have interfitting gaskets of staggered diameters. The two adjacent filters may be assembled with the smaller diameter gasket end at the base of the upper filter and the larger diameter gasket end at the top of the lower filter, so one gasket fits inside the other. Then the filters are clamped together using these clamps. In one embodiment, each clamp comprises a pair of stacking clips, plus a carriage bolt, washer and Nyloc nut. The nuts of these are tightened gradually around the filter to keep the gaskets compressed evenly. The only tool needed is a common hex head wrench. In other embodiments, spring clamps or double-hooked draw latch clamps may be used.
A large variety of filter combinations are possible, depending upon the filter area needed for a given application. The filter cartridges can be stacked one atop the other to achieve a filter assembly having the desired filter area.
In the illustrated embodiment described below, each of the clips comprises two hooked legs that fit over (or under) the circumferential flange of the cylindrical cartridge filter. A cutout or pocket formed between the two legs allows for curvature of the cap of the cartridge filter on which the clip is attached. The two legs are bent up from a horizontal flange with a square recess to receive the head of a carriage bolt. The clamp easily assembled from the two clips plus a carriage bolt, a washer and a retaining nut, as disclosed generally.
The cartridge filters as employed in this illustrated embodiment are 18 inches in diameter, and either a nominal 19 or 19.5 inches in length or a nominal 39 inches in length. The stacking system can be used with filters of other dimensions, smaller or larger diameter than what is shown here. These need not be cylindrical, but may be of square, rectangular or oval section. There can be other lengths of the filters as well, and the stacked filters can be formed with three, four, or more individual filter components. Also, other styles of clamps or clips may be employed to join the stacking filter components, e.g., variable tension draw latch clamps.
The modular stacking filter arrangement can be employed in a dust collection system in which dust in an air stream is passed through a final filter back into the ambient air. The improvement of this invention permits final filter to be formed of a stack of filter components of similar cross section, at least a first and a second filter module, and each with an end cap defining an opening into a core of the filter module and an outer rim. Typically there is at least one gasket supported on at least one such end cap, and favorably interfitting gaskets on the two end caps. In the stack, the first and second filter modules have their end caps facing one another with the gasket(s) compressed between them. A plurality of clamp assemblies distributed at regular intervals about the circumference of the stacked filter modules have portions that hook over the end caps or are otherwise attached to the end caps, and each including a member to draw the facing end caps towards one another compressing the gasket(s) between them. In a favorable embodiment, these clamp assemblies can be formed of a simple and inexpensive arrangement of two hook-flange clips each of which has a square aperture in a flange portion. Carriage bolts fit through the square apertures of the two clips, and are held in place using a washer and nut. Only a single wrench is required for assembly.
Various alternative clamp arrangements, e.g., a draw clamp or a turn-cam clamp, may be used instead.
Many possible variations of this inventive feature are possible that would follow the same basic principles. The filter can be of another configuration, e.g., rectangular or oval in section. This feature can be used on either a cyclonic or on a non-cyclonic dust collector system.